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Conjugate heat transfer of laminar mixed convection of a nanofluid through an inclined tube with circumferentially non-uniform heating.

Allahyari S, Behzadmehr A, Sarvari SM - Nanoscale Res Lett (2011)

Bottom Line: Laminar mixed convection of a nanofluid consisting of water and Al2O3 in an inclined tube with heating at the top half surface of a copper tube has been studied numerically.The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector).Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical Engineering Department, University of Sistan and Baluchestan, P,O, Box 98164-161, Zahedan, Iran. amin.behzadmehr@eng.usb.ac.ir.

ABSTRACT
Laminar mixed convection of a nanofluid consisting of water and Al2O3 in an inclined tube with heating at the top half surface of a copper tube has been studied numerically. The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector). Heat conduction mechanism through the tube wall is considered. Three-dimensional governing equations with using two-phase mixture model have been solved to investigate hydrodynamic and thermal behaviours of the nanofluid over wide range of nanoparticle volume fractions. For a given nanoparticle mean diameter the effects of nanoparticle volume fractions on the hydrodynamics and thermal parameters are presented and discussed at different Richardson numbers and different tube inclinations. Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.

No MeSH data available.


Related in: MedlinePlus

Fully developed axial velocity and temperature profile.
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Figure 6: Fully developed axial velocity and temperature profile.

Mentions: To see how the axial velocity profile is affected by the secondary flows, Figure 6 is presented. This figure shows the effect of tube inclination and the Richardson number on the axial velocity profile and dimensionless temperature profile. At α = 0, increasing the Richardson number shifts the position of maximum axial velocity toward the bottom section. Since, the strength of secondary flow augments with the Richardson number. As intended, by increasing the Richardson number the bottom half of tube is also more affected by the energy that is transferred from the top half of tube. The temperature variation at the tube cross-section augments. By increasing the tube inclination temperature variation at the tube cross-section becomes more uniform. The latter tends to shift the maximum axial velocity towards the upper part of tube. Where, axial component of the buoyancy forces is more important.


Conjugate heat transfer of laminar mixed convection of a nanofluid through an inclined tube with circumferentially non-uniform heating.

Allahyari S, Behzadmehr A, Sarvari SM - Nanoscale Res Lett (2011)

Fully developed axial velocity and temperature profile.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211450&req=5

Figure 6: Fully developed axial velocity and temperature profile.
Mentions: To see how the axial velocity profile is affected by the secondary flows, Figure 6 is presented. This figure shows the effect of tube inclination and the Richardson number on the axial velocity profile and dimensionless temperature profile. At α = 0, increasing the Richardson number shifts the position of maximum axial velocity toward the bottom section. Since, the strength of secondary flow augments with the Richardson number. As intended, by increasing the Richardson number the bottom half of tube is also more affected by the energy that is transferred from the top half of tube. The temperature variation at the tube cross-section augments. By increasing the tube inclination temperature variation at the tube cross-section becomes more uniform. The latter tends to shift the maximum axial velocity towards the upper part of tube. Where, axial component of the buoyancy forces is more important.

Bottom Line: Laminar mixed convection of a nanofluid consisting of water and Al2O3 in an inclined tube with heating at the top half surface of a copper tube has been studied numerically.The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector).Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical Engineering Department, University of Sistan and Baluchestan, P,O, Box 98164-161, Zahedan, Iran. amin.behzadmehr@eng.usb.ac.ir.

ABSTRACT
Laminar mixed convection of a nanofluid consisting of water and Al2O3 in an inclined tube with heating at the top half surface of a copper tube has been studied numerically. The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector). Heat conduction mechanism through the tube wall is considered. Three-dimensional governing equations with using two-phase mixture model have been solved to investigate hydrodynamic and thermal behaviours of the nanofluid over wide range of nanoparticle volume fractions. For a given nanoparticle mean diameter the effects of nanoparticle volume fractions on the hydrodynamics and thermal parameters are presented and discussed at different Richardson numbers and different tube inclinations. Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.

No MeSH data available.


Related in: MedlinePlus